Mechanochemical synthesis of nanocrystalline fluorinated hydroxyapatite

Synthetic hydroxyapatite (Ca-10(PO4)(6)(OH)(2), HA) is an important material used for orthopaedic and dental implant applications. The biological hydroxyapatite in the human bone and tooth is of nano size and differs in composition from the stiochiometric HA by the presence of other ions such as carbonate, magnesium and fluoride, etc. Osseointegration is enhanced by using nanocrystalline HA. This stimulates the interest in synthesizing nanocrystalline HA by different routes and among the methods, mechanochemical seems to form fine grain size and uniform characteristic nanocrystalline materials. Fluorinated hydroxyapatite (FHA, Ca-10(PO4)(6)(OH)(2-x)F-x) possesses higher corrosion resistance in biofluids than pure HA and reduces the risk of dental caries. The present work deals with the synthesis of nanocrystalline FHAs by mechanochemical processing. The nanomaterials were characterized using X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) methods. Nano FHA of about 27-46 nm size was observed. The functional groups present in the FHA powders were ascertained by Fourier transform infrared spectroscopy (Fr-IR) and Laser Raman spectroscopy. A gradual decrease in intensity of the OH- band at 655 and 3572 cm(-1) has been observed with increasing fluorine substitution. The TEM micrograph shows that the powder is highly agglomerated and particle size is below 50 nm.